Containers of this kind have to be mechanically stable, resistant to corrosion and tightly closed. These containers include a vessel and a closing cover. The tight closure is obtained with the closing cover which is fitted into the opening and welded to the vessel wall. This seal is in the form of a continuous welding seam extending about the periphery of the cover and must define a seal-tight closure with respect to the atmosphere over a practically unlimited time. Accordingly, the highest requirements are placed upon this seal. In this connection, it is not only the quality of the weld which is of concern, but, also the resistance of the weld to unintended external forces acting thereupon.
The seal or more specifically, the continuous weld seam between the sealing cover and the wall of the vessel should be made safe against mechanical damage.